A gigantic red scorpion approaches from the west. If you pull up out of the trapdoor on the left (west) side, draw weapons, and immediately sidestep to the right...

...you can shoot the scorpion as it approaches.

Three normal grenades or one super grenade will destroy it, but you can also use the shotgun, etc.

Try not to let the scorpion get too close. In addition to doing physical damage, its sting will poison Lara, causing her health bar to turn green and gradually drain away until you use a medipack.

Head downhill to the intersection of paths and turn left (south).

There's another giant scorpion attacking a soldier. The soldier is friendly enough if you don't harm him, but if you do kill him—or wait for the scorpion to do it...

...you'll get some extra revolver ammo.

Backtrack to the intersection, then go left (west).

Pick up a large medipack ahead on the right.

Then come back to the intersection again. Turn left (north) toward the deep pit.

Take a running jump across the pit on the left side.

Follow the path between the rocks.

Just around the next corner to the right...

...there's another giant scorpion. Kill it and continue to the break in the wall on the north side. You'll need to cross another pit to get to the base of the pyramid.

Take a running jump across the pit on the right side to grab the ledge. Pull up, run forward a little and turn left...

...to spot another giant scorpion rushing toward you. Kill it.

Then turn around and deal with one of those huge nasty beetles. The shotgun works great on the bugs, but of course you can use pistols if necessary.

[Menkaure's Pyramid Walkthrough]